Telephone system.



H. P. CLAUSEN.

TELEPHONE SYSTEM.

APPLICATION FILED SEPT. 22. 1916.

Patented Nov. 13, 1917.

/n ven for; Henry F. 6/6; Mae/1 panying drawing UNITED STATES PATENT OFFICE.

HENRY P. CLAUSEN, 0F MOUNT VERNON, NEW YORK, ASSIGNOR TO WESTERN ELECTBIG COMPANY, INCORPORATED, OF NEW YORK, N. Y1, A CORPORATION-0F NEW YORK- TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Nov. 13, 1917.

To all whom it may concern:

Be it known that I, HENRY P. CLAUSEN, a citizen of the United States, residing at Mount Vernon, in the county of Westchester and State of New York,.have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This inventionv relates to telephone exchange systems, and more particularly to such systems of the central energy type.

The object of this invention is to provide improved signaling meansfor such systems, and to reduce the Work of an operator in establishing a connection between subscribers lines, whereby the service is greatly improved.

In accordance with the general features of this invention, a connecting circuit, used in establishing 'connections between telephone lines, is provided with a listeningkey the position of which determines which of a plurality of stations on a line is to be signaled. This is preferably accomplished by means of switching mechanism in the form of a relay controlled by the listening key, there being two sources of signalin current the connection of which to a telephone line tobe called is directly controlled by the switching mechanism.

This invention is illustrated in the accomin which there are shown ordinary telephone lines A and B, to the former of which is connected a single subscribers station, and to the latter two subscribers stations D and E. There is. also shown a cord circuit C, embodying the present invention, used for interconnecting the telephone lines.

In the cord circuit there is a listening key 5 in either of whose actuated (and looking) positions an operators telephone set is connected to the strands of the cord circuit. Also, associated with the cord circuit are two generators 7 and 8, which furnish ringing current of 16% and 33% cycles respectively.

The listening-key 5, through the action of a slow-release relay 6 controlled thereby, controls and thereby determines which of the generators shall be effective for furnishing ringing current to the called line. The call bells of the stations on the single party lines and those of the first station (such as D) on arty lines, are tuned to respond to 16% cyc e ringing current, while the call bells of the second station (such as E) on party lines, are tuned to respond to 33%, cycle ringing current. The operator is instructed to and does listen in by throwing the listening key forward, thereby closing the left-hand set of contacts of the listening key. In this positlon of the listening key the relay 6 is normal and generator 7 is connected with the cord circuit. If the called-for line is a single party line, or if the first party on the party line is desired, the operator merely has to insert the calling plug of the cord circuit into the jack of the wanted line, whereupon the call bell of the wanted station will be operated. Should the desired station be the second station on a party lii1e,th e operator will pull the listening-key over, thereby opening the left-hand set and closing the right-hand set of contacts. The relay 6 will then operate to connect generator 8 with the cord circuit, so that upon the insertion of the calling plug into the jack of the desired line, the call bell of the second station thereon will be operated.

Associatedwith the listening key and controlled by relay 6 are two indicating lamps 9 and 10, the former-of which maybe red and the latter green, corresponding respectively to the generators? and -8. These two lamps, when the listening key is thrown forward, advlse the operator which source of ringing current hasbeen connected to the called line.

Assuming that the subscriber on line A desires to converse with subscriber D on line B, A will signal the central ofiice in the usual manner, whereupon the operator will insert the answering plug of the -cord circuit G into the jack associated with As line, causing the operation of rela 15 and su ervisory relay 16 and cut-o relay 17. he

operator may now actuate the listening key 5 by throwing it forward, closing contacts 18,19 and 20, the first two ofwhich connect the operators telephone set with the strands of the cord circuit. Finding the desired number to be that of subscriber D online B,

the operator inserts the calling plug of the cord circuit into the jack associated with line B. Relay 21- and cut-0E relay-22 are thereupon operated. The operation of.relay 21 causes the calling supervisory lam 23 to light, and connects ringing current rom generator 7 to the called line. This circuit may be traced. from generator 7 through the right-hand normal contact of relay 6,

winding of tripping relay 24, right-hand alternate contact of relay 21, middle normal contact of relay 25, tip contacts of the calling plug and jack, out over one side of line B, through the call bells of stations D and E, back over the other side of line B, ring contacts of the jack and plug, lower normal contact of relay 25 and resistance 30 through battery to ground. Upon the operation of relay 21 and with the listening key thrown forward, the red lamp 9 will be lighted over a circuit from battery through the lamp 9, the left-hand normal contact of relay 6, contact 20 of the listening key 5 and left-hand alternate contact of relay 21 to ground. This red lamp 9 indicates to the operator that generator 7 is connected to the cord circuit. At any time after the calling plug is inserted in the jack, the listening key may be returned to normal position. Since the call bell at station D is the only one on line B tuned to respond to 16% cycle ringing current, this call bell will be operated, while that at station E will not be operated. Upon the removal of the receiver at station D, in response to the operation of the call bell, relay 24 operates, whereupon relay 25 Will operate over a circuit from battery, through the winding of relay 25, resistance 31, lefthand alternate contact of relay 21 to ground. The operation of relay 25 disconnects ringing currents from the line and closes through the talking circuit, whereupon supervisory relay 32 operates to efiace the calling supervisory lamp 23. 7

Should the operator have been advised that connection is desired with station E on line 13, she would have immediately pulled the listening key in the other direction,thereby opening contacts 18, 19 and 20 and closing contacts 35, 36 and 37. The closure of contact 37 causes the operation of relay 6 over a circuit from battery through the winding of relay 6, contact 37 of listening key 5 and the left-hand normal contact of relay 21 to ground. The operation of relay 6 opens its normal contacts and closes its alternate contacts, the middle alternate contact of which prepares a locking circuit for this relay. The opening of the right-hand normal contact of this relay disconnects generator 7 from the cord circuit, and the closure of the right-hand alternate contact of this relay connects generator 8 to the cord circuit. The operator now inserts the calling plug into the jack associated with line B, whereupon relays 21 and 22 operate as before. Ringing current from generator 8 is now connected to the line and the call bell at station E will be operated. The operation of relay 1 opens the energizing cir cu t of relay 6 and completes a locking circuit therefor from battery through the winding of relay 6, the middle alternate contact thereof and the left-hand alternate contact of relay 21 to ground. The response of the called party causes ringing current to be tripped, as before described. After the insertion of the calling plug into the jack of line B, the operator restores the'listening key to normal, whereupon all contacts thereof are opened.

After completing a connection, the operator may determine at any time which of the two sources of ringing current have been connected to the called line. This may be determined by throwing the listening key forward, whereupon, if relay 6 is in its actuated position, the green lamp 10 will be lighted over a circuit from battery through lamp l0, left-hand alternate contact of relay 6, contact 20 of the listening key 5, and lefthand alternate contact of relay 21 to ground. The lighting of this lamp indicates to the operator that generator 8 had been connected to the called line. If relay 6 had been in its normal and unactuated condition, the red lamp 9 would have lighted upon the throwing forward of the listening key 5 thereby indicating that generator 7 had been connected to the called line. The lighting of one or the other of these two lamps may also indicate to the operator that station 1 or station 2 of the party line has been called.

By the use of a system embodying the present invention the two ringing buttons which are usually required in semi-selective ringing systems are not needed. By eliminating these two buttons the work of the operator in completing the connections is simplified in that she has only one key to manipulate, and less time is thereby required in establishing connections between two subscribers.

What is claimed is:

1. A telephone exchange system comprising a plurality of telephone lines, a plurality of stations on each line, a connecting circuit for interconnecting the lines, an operators telephone set, a listening key having a plurality of operative positions for associating the operators telephone set with the connecting circuit when the key is in any of said operative positions, a source of ringing current, and switching mechanism controlled by the listening key in any one of said operative positions for determining the station of a called line to be signaled.

2. A telephone exchange system comprisa ing a calling and a called telephone line, two stations on the called telephone line, a connecting circuit for interconnecting the lines, an operators telephone set, a listening key having two operative positions for associating the operators telephone set with the connecting circuit when the key is in either of said operative positions, a source of ringing current, and switching mechanism controlled by the listening key in either of said operative positions for determining the station on the called line to be signaled. r

3. A telephone exchange system comprising telephone lines, a plurality of stations on,

switching mechanism controlled by the listening key in any otsaid operative positions for determining the station of a called line to be signaled, and a plurality of signaling devices, one corresponding to each station on the called line, jointly controlled by the switching mechanism and the listening key.

4. A- telephone exchange system comprising telephone lines, a connecting circuit for interconnecting the lines, an operators telephone set, a listening key having a plurality of operative positions for associating the operators telephone set with the connecting circuit when the key is in any of said operative positions, a plurality of sources of signaling current, and switching mechanism controlled by the listening key in any of said operative positions for determining the source of signaling current to be connected to a called telephone line.

5. A telephone exchange system comprising telephone lines, a connecting circuit for interconnecting the lines, an operators. telephone set, a listening key for associating the v operatorstelephone set with the connecting circuit, a plurality of sources of signaling current, switching mechanism controlled by the listening key for determining the source of signaling current to be connected to a called telephone line, and a signaling device corresponding to each source of signaling current jointly controlled by the switching mechanism and the listening key.

6. A telephone exchange system comprisingtelephone lines, a connecting circuit for interconnecting the lines, an operators telephone set, a listening key for associating the operators telephone set with the con-' necting circuit, a plurality of sources of signaling current, and a slow-releasing relay controlled by the listening key for determining the source of signaling current to be connected to a called telephone line.

7. A telephone exchange system comprisingtelephone lines, a connecting circuit for interconnecting the lines, an operators telephone set, a listening key for associating the operators telephone set with-the connecting circuit, a plurality of sources of signaling current, a slow-releasing relay controlled by the listening key for determining the source of signaling current to be connected to a called telephone line, a signaling device corresponding to each source of signaling current, and an operating circuit for each sig naling device including contacts on the slowreleasing relay and the listening key.

In witness whereof, I hereunto subscribe my name this 20th day of September A. 1).,

HENRY P; CLAUSEN. 

